Known charging devices are designed to support, to rotate and to pivot the chute. Typically, rotation and pivoting is about two respective perpendicular axes so as to distribute bulk material in circumferential and radial directions, e.g. on a charging surface inside a blast furnace. In a widespread design, the chute used in this kind of charging device has a chute body, in which at least a downstream chute portion or even all of the chute body is of elongated shape and extends along a longitudinal axis. The chute body defines, at least at its downstream portion, a usually concave internal sliding surface, e.g. a semi-cylindrical or rectangular trough-shaped surface, on which charge material slides during operation. The chute body also defines an outlet at its downstream end, at which charge material leaves the chute body. At its opposite, upstream end, the chute usually has two suspensions, i.e. means for suspending the chute to the charging device. In order to rotate the chute, the charging device has a rotor that is rotatable, e.g. about the vertical central axis of the furnace, and two opposite support flanges for supporting the chute. The support flanges cooperate with the two lateral suspensions on the chute to hold the chute at its upstream end. In order to set the extent of radial distribution, the support flanges are pivotable about the pivoting axis in two directions, namely in a raising sense for raising the chute outlet to a radially outermost charging position and in an oppositely directed lowering sense for lowering the outlet to a radially innermost charging position with respect to the rotational axis. In case of blast furnace charging, the outermost charging position corresponds to so-called “wall charging” close to the furnace shell. The innermost charging position is used for so-called “center charging” e.g. for creating a coke chimney.
A very widespread chute design of this type is known e.g. from U.S. Pat. No. 5,513,581 or European patent EP 0 640 539. For mounting the chute onto corresponding support flanges of the charging device, this chute has two lateral suspensions (also referred to as “suspension devices”) of so-called “duckbill shape”. Duckbill shaped suspensions, already known from German patent application DE 3342572 and also illustrated in U.K. patent GB 1 487 527, have proven very satisfactory in practice and been widely used for several decades. However, they require a rather complex mounting and dismounting procedure. This procedure includes installing a handling device, lifting the outlet end of the chute, pivoting the support flanges, tilting the chute, lowering into the furnace, etc. Special handling devices have been described e.g. in Luxembourg patent LU 65663 and also in PCT patent application WO 01/18255. Such counter-balancing devices are necessary among others because the chute must be held in position underneath the charging device before its specifically shaped suspensions can be fixed to the support flanges. Of course, the risk of dropping the chute during the procedures must definitely be avoided.
With the aim of improving over these known drawbacks, a new kind of chute suspension has been described in WO 2010/028894. This kind of chute is shown in enclosed FIG. 2. It has suspensions of generally hook-shaped design with abutment and counter-abutment surfaces. The latter counteract torque exerted onto the support flanges of the charging device when the chute is mounted. As will be understood, the chute is supported at one side only in nearly “cantilevered” manner generally at the end opposite its outlet. Accordingly, considerable chute weight plus that of sliding charge material exerts considerable torque onto the support flanges of the charging device. This torque would naturally tend to jam the chute with respect to the support flanges. There are two main benefits of a chute with suspensions as shown in enclosed FIG. 2. The hook-shaped suspensions minimize the risk of inadvertent dropping of the chute during the final and initial phases of mounting and dismounting respectively. Secondly, no additional counter-balancing devices are necessary.
As will be understood from the foregoing however, commonly used chute suspension designs, e.g. of “duckbill-shaped” or hook-shaped configuration, are usually of complex shape, which in turn renders intricate or complex the movement or relative motion needed for mounting and dismounting. In addition to complex geometries of the suspension and of the support flange, the tilting torque that the chute weight exerts onto the support flanges impedes mounting and dismounting.
Another simplified known design of a chute and of chute suspensions is disclosed in U.S. Pat. No. 5,022,806 and illustrated in enclosed FIG. 1. This chute has a trough-shaped chute body of generally rectangular cross-section. The chute body is entirely of elongated shape and extends along a longitudinal axis for channeling a flow of bulk material on a sliding surface towards the chute outlet. As a suspension on each side, this chute possesses two lateral pins capable of sliding into and of being retained by corresponding grooves in each support flange. The chute according to U.S. Pat. No. 5,022,806 can be retained with its suspensions engaged in the flanges due to its own weight. As a prominent feature according to U.S. Pat. No. 5,022,806, mounting and dismounting of the chute can be achieved simply by pulling or inserting the chute along its longitudinal axis, once the support flanges have been pivoted into the required replacement position. Even with a simplified suspension design according to U.S. Pat. No. 5,022,806 however, the tilting torque of the chute onto the support flanges still hampers mounting and dismounting.